The unit may be used to heat or cool full time, but can also be adjusted to switch from heater to cooler using an added thermostat controller. The units, built to UL Nema 4X, 12 and 13 standards, have few moving parts (only fans), no filters to change, and do not require use of chlorofluorocarbons. The stainless steel design is rugged enough to stand up to harsh conditions, says the vendor, and its lightweight and compact size is designed to provide maximum benefit without sacrificing space.